Secondary wave phenomena following an underwater explosion

Underwater explosions produce a powerful shock wave followed by a secondary pressure wave, which results from the contraction of the gaseous products created by the explosion. Analytical tools were employed in order to find the variation of the secondary wave pressure as a function of time for 60 lbs of HBX-1 explosive at a 7.315m(24 ft) depth of detonation. These tools included the Navier-Stokes equations, the volume-of-fluid model of two-phase flow, and the so-called similarity equations, which are experimentally derived and embody the behavior of the shock wave and the period of the secondary wave. Heat-transfer phenomena were carefully assessed, and it was found that both the magnitude of the maximum pressure and the time of its occurrence are highly insensitive to heat transfer. During its evolution, the shape of the bubble created by the explosion passes through a range of significantly different geometries. At a time equal to half the bubble period, the shape is more or less spherical. At the end of a full period, the bubble is toroidal in shape. Owing to the buoyancy of the bubble, it experiences a vertical rise as a function of time. The maximum rise is approximately 2 m. The rising bubble causes the displacement of the surface of the water.